SyntaxPacket[integer] is a MathLink packet where integer indicates the position at which a syntax error was detected in the input line.
TabFilling is an option for character selections that specifies how a Tab character is represented on the screen.
TargetFunctions is an option for functions such as ComplexExpand that specifies what functions to attempt to generate in the output.
TokenWords is an option for Read and related functions which gives a list of token words to be used to delimit words.
Top
(Built-in Mathematica Symbol) Top is a symbol that represents the top for purposes of alignment and positioning.
TrigFactorList[expr] factors trigonometric functions in expr, yielding a list of lists containing trigonometric monomials and exponents.
UnderoverscriptBoxOptions -> {opt_1 -> val_1, opt_2 -> val_2, ...} is an option for selections that specifies settings for UnderoverscriptBox objects.
UnderscriptBoxOptions -> {opt_1 -> val_1, opt_2 -> val_2, ...} is an option for selections that specifies settings for UnderscriptBox objects.
UpdateInterval is an option to Refresh and Dynamic that specifies at what time interval to do updates.
WhitespaceCharacter represents a single whitespace character in StringExpression.